* Add Ruby linter with Steep
Fixes#3254
* Run steep instead of using language server
LSP presents a few issues and this works around those.
* Work around Steep path issue
See https://github.com/soutaro/steep/pull/975
* Add simple tests for steep
* Add steep to supported tools
* Pass linter
* Add a comment regarding Steep's column counting
* Make lnum an integer
* Add Steep handler test
* Fix separator for Windows
* Escape Windows path separators for substitute()
* Use ALEInfo (I) group
* Use fnameescape instead of quotes
* Skip linting for files not under steep root
* Add and pass tests covering proper steep root lookup
* Fix separator discrepancy
* Use strict operators (match case)
* Fix ordering
* Use `is#` instead of `==#`
Loic Nageleisen